The CIA wanted assurance that the techniques would not violate laws against torture.
Bybee provided that assurance in chillingly detached prose. Here are some highlights:
Prolonged sleep deprivation is acceptable because "it cannot be said to constitute a threat of severe physical pain or suffering from the perspective of a reasonable person in Zubaydah's position." Indeed, "it is not uncommon for someone to be deprived of sleep for 72 hours and still perform excellently on visual-spatial motor tasks. ... In one case, even after 11 days of deprivation, no psychosis or permanent brain damage occurred. ... [T]he effects remit after a few good nights of sleep."
"Cramped confinement" for up to 18 hours in complete darkness in a "container" just large enough for "the individual" to "stand up or sit down" is fine because "[w]e have no information ... that the limited duration for which the individual is kept in the boxes causes any substantial physical pain," and "the use of the confinement boxes does not constitute a procedure calculated to disrupt profoundly the senses or personality."
It's OK to put insects in Zubaydah's confinement box, knowing "he appears to have a fear of insects," because, "though the introduction of an insect may produce trepidation in Zubaydah ... it certainly does not cause physical pain." However, it's best not to tell him there will be insects in the box: "If you do so ... you must inform him that the insects will not have a sting that would produce death or severe pain."
"A variety of stress positions may be used" for long periods because they merely "involve the use of muscle fatigue to encourage cooperation and do not themselves constitute the infliction of severe physical pain or suffering."
Go ahead and waterboard him. Admittedly, the procedure "causes an increase in carbon-dioxide level in the individual's blood. This increase in the carbon-dioxide level stimulates increased effort to breathe. This effort plus the cloth [placed over the mouth and nose and saturated with water] produces the perception of 'suffocation and incipient panic,' i.e., the perception of drowning." But "although the subject may experience the fear or panic associated with the feeling of drowning, the waterboard does not inflict physical pain. ... The waterboard is simply a controlled acute episode."